Currently screening for dementia includes, for example: a revised version of Hasegawa's Dementia Scale (HDS-R), as described in “Katoh, S., Simogaki, H., Onodera, A., Ueda, H., Oikawa, K., Ikeda, K., Kosaka, K., Imai, Y., and Hasegawa, K.: Development of the revised version of Hasegawa's Dementia Scale (HDS-R), Japanese Journal of Geriatric Psychiatry, Vol. 2, No. 11, pp. 1339-1347 (1991), (in Japanese)”; Mini-Mental State Examination (MMSE) as described in “Folstein, M. F., Folstein, S. E., and McHugh, P. R.: “Mini-Mental State”: A practical method for grading the cognitive state of patients for the clinician, J. Psychiat. Res, Vol. 12, No. 3, pp. 189-198 (1975)”; and Clinical Dementia Rating (CDR) as described in “Morris, J. C.: The Clinical Dementia Rating (CDR): Current version and scoring rules, Neurology, Vol. 43, No. 11, pp. 2412-2414 (1993). Such dementia screening methods are similarly widely used to tests based on neurophysiology such as functional MRI (fMRI), FDG-PET, and CSF biomarkers, as described in “Zhang, D., Wang, Y., Zhou, L., Yuan, H., Shen, D., and The Alzheimer's Disease Neuroimaging Initiative: Multimodal classification of Alzheimer's disease and mild cognitive impairment, Journal of Neuroimage, Vol. 55, No. 3, pp. 856-867 (2011)”.
These are performed by doctors who have received a given amount of training or clinical physicians, mainly in medical institutions.
However, in the normal outpatient scenario, although these are simple investigations, such as HDS-R, a doctor takes about 5 to 20 minutes to perform the investigation. It is accordingly pointed out that this has a negative impact on the treatment of other outpatients, with consideration given to the need to reduce the burden on doctors.
For example, known tests based on neurophysiology such as fMRI, FDG-PET and CSF biomarkers mentioned above are described in “The Alzheimer's Disease Neuroimaging Initiative: Multimodal classification of Alzheimer's disease and mild cognitive impairment, by Zhang, D., Wang, Y., Zhou, L., Yuan, H., Shen, D., and Journal of Neuroimage, Vol. 55, No. 3, pp. 856-867 (2011)”. Although these tests are non-invasive, due to the many limitations, such as the difficulty of taking spinal fluid samples, radiation exposure, the large size of measurement apparatus, and the need to restrain test subjects, they are not suitable for mass early stage screening of elderly people.
If a tool could be developed that was more simple and easier to use, and also had equivalent performance or better than that of existing tools, physicians would then be able to further widen the scope of implemented screening. This would accordingly enable a contribution to be made to early stage diagnosis of dementia.
In previous research (Japanese Patent Application Laid-Open (JP-A) No. 2011-255106) and “Preliminary Study of Speech Prosody-Based Relationship with HDS-R Scores Toward Early Detection of Cognitive Impairment in Elderly Using Speech Prosody by Shohei Kato, Yuta Suzuki, Akiko Kobayashi, Toshiaki Kojima, Hidenori Itoh, Akira Homma; Transactions of the Japanese Society for Artificial Intelligence; Vol. 26; No. 2, pp. 347-352 (2011)), the present inventors have researched screening of cognitive impairment by observing spoken speech of elderly people and using speech prosodic characteristics. This technology has the advantage that, due to using only voice data, it can be implemented on anyone irrespective of location, such as at home or during a visit (in primary screening).